The present invention relates to stick-type cosmetic compositions. More particularly, it relates to improved deodorant sticks.
The chemical and cosmetic literature is replete with formulations of stick-form cosmetics for various uses, such as antiperspirants, deodorants, and lipsticks. The specific stick formulation may vary depending upon such factors as the intended use, the "active" ingredient to be incorporated, and the part of the body to which the product is to be applied.
There are three main types of such cosmetic stick formulations: compressed power sticks, gel sticks, and wax sticks. While each of these formulation types may have advantages in certain use situations, each also has disadvantages. For example, compressed powder sticks are often brittle and hard, and leave a cosmetically-unacceptable dust upon application. Gels, while offering very good aesthetic characteristics, may be unstable due to interaction of the soap gelling agents typically used to solidify such sticks with the stick's "active" material (e.g., the astringent metallic salts used in antiperspirant sticks). Wax-based formulations can also yield cosmetically-unacceptable products due to such factors such as hardness, greasiness, and stickiness. The opacity of such wax sticks, and the residue created in their use, may also be aesthetically undesirable.
Many stick formulations have been described in the literature which attempt to maintain the desirable cosmetic and aesthetic attributes of gel sticks, while minimizing the disadvantages of gel sticks. For example, antiperspirant gel sticks, using dibenzaldehyde monosorbitol acetal (herein "DBMSA") as a gelling agent, are described in U.S. Pat. No. 4,154,816, Roehl, et al., issued May 15, 1979, U.S. Pat. No. 4,346,079, Roehl, issued Aug. 24, 1982, and U.S. Pat. No. 4,518,582, Schamper, et al., issued May 21, 1985. Deodorant sticks using DBMSA are described in Japanese Pat. No. 50/52,007, published Apr. 9, 1975. Nevertheless, it has been found that such DBMSA sticks, while avoiding the use of soaps, may produce sticks of aesthetically unacceptable softness. While hardness of such sticks may be increased by use of increased levels of DBMSA, such levels may require excessive heating of product materials during manufacturing so as to fully solubilize the DBMSA. The use of such high levels, with heating, presents disadvantages due to cost, safety, and thermal degradation of some materials, such as "active" materials or fragrances. Hardness can also be increased using other gelling agents (such as sodium stearate) with DBMSA, but also incurring the disadvantages associated with such other agents, as described above.
It has now been discovered that solid cosmetic sticks using DBMSA as a gelling agent, and also containing certain fatty alcohols, are cosmetically and aesthetically acceptable sticks. In particular, such sticks of this invention afford gel rheologic characteristics and gel transparency, while maintaining hardness and physical integrity more typical of wax-based cosmetic sticks. Such benefits can be obtained without using disadvantageous levels of DBMSA and/or other gelling agents.